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DOI | 10.5194/acp-20-15811-2020 |
Chemical composition and source apportionment of atmospheric aerosols on the Namibian coast | |
Klopper D.; Formenti P.; Namwoonde A.; Cazaunau M.; Chevaillier S.; Feron A.; Gaimoz C.; Hease P.; Lahmidi F.; Mirande-Bret C.; Triquet S.; Zeng Z.; Piketh S.J.; Stuart.piketh@nwu.ac.za | |
发表日期 | 2020 |
ISSN | 1680-7316 |
起始页码 | 15811 |
结束页码 | 15833 |
卷号 | 20期号:24 |
英文摘要 | The chemical composition of aerosols is of particular importance to assess their interactions with radiation, clouds and trace gases in the atmosphere and consequently their effects on air quality and the regional climate. In this study, we present the results of the first long-term dataset of the aerosol chemical composition at an observatory on the coast of Namibia, facing the south-eastern Atlantic Ocean. Aerosol samples in the mass fraction of particles smaller than 10 m in aerodynamic diameter (PM10) were collected during 26 weeks between 2016 and 2017 at the ground-based Henties Bay Aerosol Observatory (HBAO; 22±60 S, 14±300 E; 30m above mean sea level). The resulting 385 filter samples were analysed by X-ray fluorescence and ion chromatography for 24 inorganic elements and 15 water-soluble ions. Statistical analysis by positive matrix factorisation (PMF) identified five major components, sea salt (mass concentration: 74:7±1:9%), mineral dust (15:7±1:4%,), ammonium neutralised (6:1±0:7%), fugitive dust (2:6±0:2%) and industry (0:9±0:7%). While the contribution of sea salt aerosol was persistent, as the dominant wind direction was southwesterly and westerly from the open ocean, the occurrence of mineral dust was episodic and coincided with high wind speeds from the south-south-east and the north-north-west, along the coastline. Concentrations of heavy metals measured at HBAO were higher than reported in the literature from measurements over the open ocean. V, Cd, Pb and Nd were attributed to fugitive dust emitted from bare surfaces or mining activities. As, Zn, Cu, Ni and Sr were attributed to the combustion of heavy oils in commercial ship traffic across the Cape of Good Hope sea route, power generation, smelting and other industrial activities in the greater region. Fluoride concentrations up to 25 gm3 were measured, as in heavily polluted areas in China. This is surprising and a worrisome result that has profound health implications and deserves further investigation. Although no clear signature for biomass burning could be determined, the PMF ammonium-neutralised component was described by a mixture of aerosols typically emitted by biomass burning, but also by other biogenic activities. Episodic contributions with moderate correlations between NO3 , nss-SO2 4 (higher than 2 gm3/ and nss-KC were observed, further indicative of the potential for an episodic source of biomass burning. Sea salt accounted for up to 57% of the measured mass concentrations of SO2 4 , and the non-sea salt fraction was contributed mainly by the ammonium-neutralised component and small contributions from the mineral dust component. The marine biogenic contribution to the ammoniumneutralised component is attributed to efficient oxidation in the moist marine atmosphere of sulfur-containing gas phase emitted by marine phytoplankton in the fertile waters offshore in the Benguela Upwelling System. The data presented in this paper provide the first ever information on the temporal variability of aerosol concentra-tions in the Namibian marine boundary layer. This data also provide context for intensive observations in the area. © Author(s) 2020. |
语种 | 英语 |
scopus关键词 | aerosol; atmospheric pollution; chemical composition; coastal zone; dust; fluoride; human activity; open ocean; source apportionment; statistical analysis; temporal variation; upwelling; Atlantic Ocean; Atlantic Ocean (Southeast); Namibia; Namibia |
来源期刊 | ATMOSPHERIC CHEMISTRY AND PHYSICS
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文献类型 | 期刊论文 |
条目标识符 | http://gcip.llas.ac.cn/handle/2XKMVOVA/247267 |
作者单位 | Unit for Environmental Science and Management, School of Geo and Spatial Science, North-West University, Potchefstroom, South Africa; Laboratoire Interuniversitaire des Systemes Atmospheriques (LISA), UMR CNRS 7583, Universite Paris-Est Creteil, Universite de Paris, Institut Pierre Simon Laplace, Creteil, France; Sam Nujoma Marine and Coastal Resources Research Centre (SANUMARC), University of Namibia, Henties Bay, Namibia |
推荐引用方式 GB/T 7714 | Klopper D.,Formenti P.,Namwoonde A.,et al. Chemical composition and source apportionment of atmospheric aerosols on the Namibian coast[J],2020,20(24). |
APA | Klopper D..,Formenti P..,Namwoonde A..,Cazaunau M..,Chevaillier S..,...&Stuart.piketh@nwu.ac.za.(2020).Chemical composition and source apportionment of atmospheric aerosols on the Namibian coast.ATMOSPHERIC CHEMISTRY AND PHYSICS,20(24). |
MLA | Klopper D.,et al."Chemical composition and source apportionment of atmospheric aerosols on the Namibian coast".ATMOSPHERIC CHEMISTRY AND PHYSICS 20.24(2020). |
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